Vibration isolator



April 19, 1955 E. B. ALLEN VIBRATION ISOLATOR Filed April 14, 1951United States Patent C) 2,706,606 VIBRATION ISOLATOR Ernest B. Allen,Needham, Mass. Application April 14, l1951, Serial No. 221,075 1 Claim.(Cl. 248-20) This invention relates to a device for supporting a loadfrom a substructure which will be effective in resisting transmission ofvibrations to the substructure. Examples of its application in use arethe support of individual machines from a foundation or, as described inan article by Francis I. Crandell in the periodical Textile Industries,issue of March 1951, for the support from the walls of a building of afloor on which a number of machines are mounted.

The objects of the invention are to provide a simple and compactconstruction which may be embodied in a structure of suitable dimensionsand inherent resistance suitable for the load which is to be carried, asdetermined in accordance with engineering principles and which willefficiently neutralize vibrations set up by the load, whatever theirdirection.

My invention will be well understood by reference to the followingdescription of the illustrative embodiment thereof as shown by way ofexample in the accompanying drawings wherein:

Fig. 1 is a plan view of the supporting device as such partly brokenaway;

Fig. 2 is a longitudinal section through Fig. 1;

Fig. 3 is a partial vertical section illustrating the mounting andtensioning of a spring; and

Fig. 4 is a plan of a spacing washer.

I shall refer to the isolator in the singular and to the load supportedthereby. It will be understood that several devices as hereinillustrated may be used cooperatively to support a load.

The illustrative embodiment of my invention shown in the drawingsembodies an upper plate 12 to which the load, that is the part subjectto vibration, is secured, as for example by means of the two parallelprojecting flanges 10, and a lower plate 14 which is mounted on thesubstructure. The flange 16 herein shown is an example of a securingdevice for such lower plate. The upper plate is supported from the lowerplate by resilient devices which resist movement of the former relativeto the latter in all directions (other than the vertically upwarddirection wherein gravity does the work) that is to say downwardly andin four directions, two relatively perpendicular to the other two, whichit might be convenient to think of as north, south, east and west, if itis understood that no actual orientation of the device with thosecompass points is thereby implied. Such a resilient support will ofcourse function against forces which may be considered as havingcomponents in the several directions mentioned.

This resilient supporting mechanism will now be more particularlydescribed. The upper plate 12 has a depending projection in the generalform of a capital letter I embodying a stem 18 and crossbars 20. Thelower plate 14 has along its sides four upstanding projections 22 in thenature of ribs, those at the top and bottom, viewing Fig. 1, parallelingthe stem 18 of the I and those at the sides, viewing that figure,paralleling the crossbars. The projections 22 overlap vertically theprojections 18 and 20 their apposed faces providing abutments for springunits which resist relative horizontal movement of the two plates. Thesespring units herein each comprise two heavy helical springs 24, theinner ends of which herein are shown as encircling and supported bybosses 26 on the depending elements 18 and 20, while their outer endsare carried by seat members 28 which are adjustably supported, as bymeans of spacing washers 30, from the upstanding projections 22 of thelower plate 14, the springs thus being interposed between and suspendedby the two plates.

It will be noted that the upper and lower spring units 24, viewing Fig.2, which bear on the stem 18 of the I-shaped projection, extend betweenand are partly accommodated in the space between the pair of springunits at the right and left in that figure. One dimension of the2,706,606 Patented Apr. 19, 1955 ICC unit is thus relatively short andconvenient for positioning transversely to a wall.

The four spring units are organized as a centric group and define spacesbetween successive pairs adjacent the corners of the plate which receivevertical supporting springs 32. The size and the tension of the springsare suitably designed in view of the loads to which they are to besubjected in use in a given case.

To permit accurate prestressing of the vertical springs verticaljackscrews 34 may project up from the lower plate, conveniently passingthrough the centers of the springs 32 and through a clearance opening 36in the upper plate. Nuts 38 may be applied to these screws to press theupper plate down toward the lower plate, imposing a desired load on thesprings equivalent to the gravity load of the structure or machine to besupported. The prestressed spring unit being secured to thesubstructure, the machine or the like is secured in position after whichthe nuts may be backed off, and if desired, discarded. It will be notedthat the jackscrews are all arranged outwardly of the flanges 10 whichin the construction shown represent the means for securing the machineor the like to the top plate. The machine may thus be positioned andsecured without interfering with the screws and the nuts are accessiblethereafter.

To provide for prestressing the horizontal springs and to facilitateinstallation, the projections 22 may be provided with tapped openings 40axially aligned with the several springs in this instance to receivesuitable jackscrews 42, as illustrated in Fig. 3. These screws may bearon the seat members 28 and when the screws are set up the members 28will be moved toward the left in Fig. 3 compressing the springs. Whenadjusted the spacing washer 30 of selected thickness, suitable for theoccasion and having a radial slot 46 (see Fig. 4) to permit it to bedropped laterally over the jackscrew is inserted between the seat 28 andthe abutment surface 22. In Fig. 3 the washer is shown as it wouldappear while being inserted in its desired position. Herein the seatmember 28 has a flange 48 which embraces the washer and holds it inposition. After the spring has been stressed to the desired degree anextra turn or two of the screw 42 will permit the washer to be droppedinto position and when these turns are backed olf the flange willencircle the washer and hold it in position.

I am aware that the invention may be embodied in other specific formswithout departing from the spirit or essential attributes thereof, and Itherefore desire the present embodiment to be considered in all respectsas illustrative and not restrictive, as is in fact clear in severalmatters from the description itself. Reference is to be had to theappended claim to indicate those principles of the invention exemplifiedby the particular embodiment described and which I desire to secure byLetters Patent.

I claim:

An isolator for supporting a load from a sub-structure and for resistingtransmission of vibration to the substructure comprising upper and loweropposed plates for underriding the load and for resting on thesubstructure respectively, a projection from one plate defining ageneral I-shape, projections at four sides of the other plateparalleling the ends and the web of the I respectively, vertical springsin the spaces between the latter projections supporting the upper platefrom the lower, and horizontal springs interposed between and terminallysupported from the apposed faces of the projections and providing ayielding resistance to movement of the upper plate relative to the lowerin each of four horizontal directions, two relatively perpendicular tothe other two.

References Cited in the file of this patent UNITED STATES PATENTS804,884 Rutan Nov. 21, 1905 1,377,556 Bridgman May 10, 1921 1,766,597Bushnell June 24, 1930 1,845,551 Mitzl Feb. 16, 1932 2,281,955Rosenzweig May 5, 1942 2,365,842 Rosenzweig Dec. 26, 1944 FOREIGNPATENTS 501,130 Great Britain Feb. 13, 1939

